Beauty is in the eye of the beholder. But quality is a matter of science. At the Gemological Institute of America, we’ve spent nearly 100 years ensuring that diamonds, colored stones, and pearls are assessed, cataloged, and graded on their quality, with unbiased scientific precision. We wrote the book on diamond grading. Our International Diamond Grading System™ is the global standard. As the home of gemological research and education, we invented many of the instruments used by the international gem and jewelry industry, and we created the 4Cs of diamond quality. Color, Clarity, Cut, Carat Weight. Today, the 4Cs scientifically ensure public trust in our industry. We do not buy, sell or appraise diamonds. As a nonprofit public benefit institute, we provide the expertise, quality reports, and verifications that everyone from miners to merchants and you can trust when making your next diamond decision. Ask for a GIA report. If they don’t have one, ask for a new jeweler.